Copper-base alloy



July 12, 1955 v. PULSIFER ETAL 2,712,992

COPPER-BASE; ALLOY Filed Nov. 16, 1953 6 Sheets-Sheet l IRON July 12,1955 Filed Nov. 16, 1953 v. PULSIFER ETAL 2,712,992

COPPER-BASE ALLOY 6 Sheets-Sheet 2 F ig. 2

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%lRoN JNVENTORS VERNE PULSIFER BYMICHAEL V. NEVITT ATTORNE July 12, 1955v. PULsu-ER ET AL 2,712,992

COPPER-BASE ALLOY Filed Nov. 16, 1955 6 Sheets-Sheet 4 Fil?. 4

O D u Y d) Y IRON NVENTORS VERNE. PULSIFER BYMlCHAEL NEVTT ATTORNE July12, 1955 v.PULs1FER ETAL 2,712,992

COPPER-BASE: ALLOY Filed Nov. 16, 1953 6 Sheets-Sheet 5 Fig. 5

INVENTORS VERNE PULSIFER BYMICHAEI. V. NEVITT ATTORNE July 12, 1955 v.PULsn-ER ET Ax.

COPPER-BASE ALLOY 6 Sheets-Sheet 6 Filed Nov. 16, 1953 United StatesPatent O CPPER-BASE ALLSY Verne Pulsiier, La Grange, Ill., and MichaelV. Nevitt, Biacitsburg, Va., assiguors to lin Mathiasen ChemicaiCorporation, a corporation of Virginia Appiicaiion November 15, 1953,Serial No. 392,076

13 Claims. (Cl. '7S-161) This invention relates to electrical conductorsformed of copper-base alloys and more particularly to such alloyssuitable for use in electric spring conductors, and the like.

Heretofore spring members for electrical connectors have ordinarily beenformed of such metals as coppercadmium alloys, copper-tin alloys, andcopper-nickelphosphorus alloys. Electrical connectors formed of suchalloys are, however, relatively expensive, due in some instances to thehigh cost of the alloying elements and in other instances to the highcost of the age-hardening treatments and the like necessary to providethe requisite electrical conductivity and strength. Such connectors havealso been formed of less expensive alloys having relatively lowelectrical conductivity, but little economy is effected by this method,since it is then necessary to employ a greater amount of such metal inorder to make the member of relatively thick cross section to avoidexcessive electrical resistance. rthe present invention has among itsobjects to provide an electrical connector composed of relativelyinexpensive alloying elements and having the electrical conductivity andstrength requisite for electric switches and the like without anyage-hardening treatments.

Another object of the invention is to provide an improved electricalconductor formed largely or" copper.

Stili another object is to provide a copper-manganeseiron-phorphorusalloy of novel composition particularly suited for use in electricalconductors for electrical switch members, electrical connectors, and thelike.

A further object is to provide an inexpensive alloy having suitablestrength and conductivity after cold working for use in electricalspring contact members and the like.

Other objects and advantages of the invention will becorne apparent fromthe following detailed description and the accompanying drawing, inwhich Figure l is a diagram illustrating the relationship between themanganese and iron contents of compositions prepared in accordance withthis invention when the phosphorus content of the alloy is about 0.2%,

Figure 2 is a diagram similarly illustrating the relationship betweenmanganese and iron contents when the phosphorus content of the alloy isabout 0.3%,

Figure 3 is a diagram similarly illustrating the relationship betweenmanganese and iron contents when the phosphorus content of the alloy isabout 0.4%,

Figure 4 is a diagram similarly illustrating the relationship betweenmanganese and iron contents when the phosphorus content of the alloy isabout 0.5%,

Figure 5 is a diagrammatic view of a radio tube and the tube socket,partly in section, containing a connector illustrating one embodiment ofthis invention,

Figure 6 is an enlarged View of the electrical connector shown in Figure5,

Figure 7 is a side View of the connector shown Figure 6, and

Figure 8 is a perspective view of a three-dimensional diagrammaticrepresentation of the rather complex bulbous volume E and the innervolume F containing all Cfr 2,712,992 Patented July 12, 1955 pointsrepresenting the percentage values of the constituents phosphorus,manganese and iron as variables in the proportions to be found in analloy having, respectively, at least the minimal essential physicalcharacteristics sought and having the preferred characteristics. Thevertical coordinant of phosphorus content is plotted on a scale enlargedby a factor of about three so as to more widely space and more clearlyshow the horizontal traces A, B, C and D.

The foregoing objects and advantages are accomplished in accordance withthis invention by providing as the metal for the electrical conductor analloy having a phosphorus content in the range from 0.16% to 0.58%, aniron content in the range from 0.02% to 0.89%, and a manganese contentin the range from 0.27% to 1.12%, with the balance copper. A preferredcomposition for the conductor in accordance with this invention is aphosphorus content in the range from about 0.19% to 0.51%, an ironcontent in the range from about 0.l5% to 0.76%, and a manganese contentin the range from about 0.47% to 0.94%, with the balance copper. Withinthe preferred range, the composition with optimum properties has beenfound to be one consisting of from about 0.33% to about 0.36%phosphorus, from about 0.42% to about 0.49% iron, from about 0.67% toabout 0.72% manganese and the balance copper.

ln order that the conductor can be made relatively thin, it is preferredthat the copper alloy have an electrical conductance or" at least 50% I.A. C. S., and in order that the conductor have the necessary resilienceand physical characteristics requisite for electrical spring connectors,it is preferred that the copper alloy have a tensile strength of atleast 75000 pounds per square inch when measured by A. S. T. M. methodE8-46. Such a combination of strength and conductance has not beenattained heretofore with copper alloy Strip without expensive alloyingingredients or age-hardening treatments. Such a combination of highstrength and conductance is obtained, however, in accordance with thisinvention by holding the phosphorus, iron, and manganese contents of thealloy within the relatively narrow ranges specified hereinbefore anddescribed in greater detail hereinafter and cold working the alloy froman annealed structure to about a 70% reduction in thickness. Thus, inaccordance with this invention, the alloy is brought to a dimensionabout three and one-third times that desired for the electricalconnector either by hot working, or cold working followed by annealing,or both, and is then reduced to the desired dimension by cold working.

Referring now to the drawing, the amounts of manganese and ironpermissible in the copper-alloy having a conductivity of at least 50% i.A. C. S. and a tensile strength of at least 75,000 pounds per squareinch after cold working from an annealed structure to 70% reduction inthickness fall within the area bounded by the line A, Figure i, when thephospho-rus content of the alloy is about 0.2%, within the area boundedby the line B, Figure 2, when the phosphorus content of the alloy isabout 0.3%, within the area bounded by the line C, Figure 3, when thephosphorus content of the alloy is about 0.4%, and within the areabounded by the line D, Figure 4, when the phosphorus content of thealloy is about 0.5%.

By way of example, a casting one-half inch thick formed of an alloycomposed of 0.37% phosphorus, 0.80% iron, and 0.58% manganese, with thebalance copper was heated to 900 C. for thirty minutes and was then hotrolled in three steps, the lirst being to a thickness oi 0.375", thesecond being to a thickness of 0.300" and the third being to a thicknessof 0.200. The 0.200 thiolr strip was then cold rolled to a thickness of0.100" and annealed at 600 C. for one-half hour. The 0.100 thick Vstripwas then cold roiied to a thickness of 0.035 in three passes through thework rolls and then annealed at 535 C. for one-half hour to provide anannealed structure. The 0.035 thick annealed strip was then finally coldrolled in YJthree passes through the work rolls to a thickness of 0.010,which amounts to a cold working to 71% reduction in thickness. The coldworked strip had a Rockwell F hardness of 100, a tensile strength of78,500 pounds per square inch and a conductivity of 66.8% I. A. C. S. Asimilar casting formed of an alloy composed of 0.29% phosphorus, 0.69%iron and 0.40% manganese with the balance copper, when treated as above,after cold working from the annealed structure to about 70% reduction inthickness had a Rockwell F hardness of 99, a tensile strength of 77,200pounds persquare inch and a conductivity of 59.9% I. A. C. S. A similarcasting formed of an alloy composed of 0.19% phosphorus, 0.14% iron, and0.63% manganese, with the balance copper, when treated as above, afterannealing and a cold reduction of about 70% in thickness had a RockwellF hardness of 101, a tensile strength of 80,200 pounds per square inchand a Vconductivity of 58.6% l. A. C. S.

Referring to the drawing, the areas bounded by the lines A, B, C, and D,in Figure l' through 4 and 8, respectively, represent cross-sectionalareas of an imaginary threedimensional volume E, Figure 8, wherein thecontent o phosphorus is measured in the direction perpendicular to theplanes shown in the respective figures. As indicated hereinbefore, theboundary lines A, B, C, and D of'the respective gures indicatecross-sections of the phosphorusiron-manganese volume E taken at 0.2%,0.3%, 0.4%, and 0.5% phosphorus, respectively. The phosphorus axis ofsaid volume terminates at a minimum of about 0.16% phosphorus and at amaximum of about 0.58% phosphorus. As vwill be seen from the drawing,this volume of compositions Vfalls within the ranges set forthhereinbefore for the amounts of phosphorus, iron, and manganese, namely0.16% to 0.58% phosphorus, 0.02% to 0.89% iron,.and 0.27% to 1.12%manganese.

It has also been found that an electrical conductor of even furtherimproved characteristics can be provided for the purpose if thepermissible amounts of the alloying'constituents are held within certainnarrow ranges. Such improvementV is obtained by providing as the metalfor the electrical conductor an alloy preferably having an electricalconductivity of at least 60% l. A. C. S. and a tensile strength of atleast 80,000 pounds per square inch after cold working from an annealedstructure to about 70% reduction in thickness and having a phosphoruscontent in the range from about 0.19% to 0.51%, an iron content-in therange from about 0.15 to 0.76%, and a i Vmanganese content inthe rangefrom about 0.47% to 0.94%, with the balance copper.

By way of example of such preferred alloy composition,

a casting one-half inch thick formed of an alloy composed of 0.182%phosphorus, 0.21% iron, and 0.57% manganese, with the balance copper,when treated as hereinabove described, after annealing and then coldworking to 71% reduction in thickness had a Rockwell F hardness of 101,a tensile strength of 82,200 pounds per square inch, and an electricalconductivity of 60.9% I. A. C. S. A similar casting formed of an alloycomposed of 0.36% phosphorus, 0.44% iron, and 0.70% manganese, with thebalancecopper, when treated as described hereinabove, after annealingand then cold working to 71% reduction in thickness, had a RockwellF-hardness of 101, a tensile strength of 81,100`pounds per square inch,and an electricalconductivity of 69.7% A. C. S.

Within the preferred range an alloy having a composition of about0.3.3-0.36% phosphorus, about 0.42-0.49% iron, and about 0.67-0.72%manganese, with the balance copper, was cast to a thickness of tiveinches and hot rolled at about 875 C. to a thickness of about half aninch. After milling, the bar was cold rolled, then annealed, at 650-620C., cold rolled again to a gage Vof 0.42 of an inch, annealed at about540 C. and finally cold rolled in four passes to a total reduction of70%. The

cold worked strip had a tensile strength from 80,200 to 80,800 poundsper square inch and a conductivity of from 67.9% to 68.3% l. A. C. S. Y

While in the foregoing examples the annealed structure prior to thefinal cold working to about 70% reduction in dimension was obtained byactual annealing prior to said nal cold working step, it is to beunderstood that the annealed structure referred to herein may likewisebe obtained as a result of a hot working. The process of this invention,therefore, is to provide the alloy with an annealed structure and adimension about three and onethird times greater than the desired finaldimension and then to cold work to about 70% reduction in dimension.Referring to the drawing, Figure 8, it may be seen that the shadedportion of the areas bounded by lines A, B, C and D in Figures l through4,'respectively, likewise represent cross-sectional areas of anYimaginary volume F contained within the volume E of Figure Y8, whereinthe content of phosphorus is measured in the direction perpendicular tothe planes shown in the respective FiguresY 1 through 4.V The shadedareas in Figures l through 4 thus represent cross-sectional areas of thephosphorus-iron-manganes'e volume F taken at 0.2%,

0.3%, 0.4%, and 0.5%, respectively. The phosphorus axis of said volumeterminates at a minimum of about 0.19% phosphorus and at a maximum ofabout 0.51% phosphorus. It Ywill be likewise noted that this innervolume representing preferred compositions falls` within the preferredranges set forth hereinbefore, namely 0.19% to 0.51% phosphorus, 0.15%to 0.76% iron, and 0.47% to 0.94%' manganese. As indicated hereinbefore,a point fall- Ving within the volume E defined by the areas bounded bylines A, B, C, and D, in theV drawing represents the percents by weightof the phosphorus, iron, and manganese permissible in the copper-alloyof this invention, which alloy after annealing and then cold working toabout 70%Y reduction in thickness has the combination of an electricalconductivity of at least.50% I. A. C. S. with a tensile strength of atleast 75,000 pounds per squareV inch. Similarly, a point within theinner volume F dened by the shaded portions of Figures 1 through 4represents the percents by weight of manganese,-iron and phosphoruspermissible in the preferred copper-alloy composition, which alloy afterannealing and then cold working to a reduction of about 70% inthicknesshas' alloys of this invention there follows a table of some Ytypical compositions which are illustrative of the invention and whichwhen plotted as points fall upon the surface of or within either or bothof the volumes E and F:

Composition n Y E 1 (Siensiin (mcxamp e Percent Percent rang PercentPacs Pnt Manm P- S- L r. A. o. s. n phOluS games@ 0. 38 0. 40 0. 5l 8l.500 54. 2 0. 34 45 O. 72 80, 000 64. 5 0. 32 0. 35 0. 67 81, 700 6l.. (l0. 29 0. 52 0. 75 81, 100 5l. 5 0. 28 0. 4l. 0. 97 78, 500 54. 4 0. 220. 14 0. 66 80, 500 57. 7

It will be apparent that the alloying ingredients namely manganese, ironand phosphorus used with the copper trical connectors and the likeprovided in accordance with this invention are relatively inexpensive.

Referring to the drawing, igures 5, 6 and 7, an electrical connector 1is shown illustrating an embodiment of this invention. Such anelectrical connector 1 is Seated in each of the slightly largerdiametered bores 2 of the radio or electronic tube socket 8. The bore 2is provided with a shoulder 9 which prevents the connector 1 from beingpushed completely down through the socket and the indent 6 on connector1 engages the bottom of socket 8 to prevent the connector 1 from beingpulled out of the bore 2. The wiring terminal portion 5 of the connectoris perforated to facilitate soldered attachment to the wiring of anyradio circuit. The expansible sleeve portion 7 is adapted for thereception of and frictional engagement with the terminal prong 3 of theradio tube 4. When made in accordance with this invention, theexpansible sleeve portion 7 of the connector 1 has ample strength,resilience, and spring-like characteristics to expand and tightly engagethe terminal prong 3. Such connectors may be formed, for example, bysubjecting an ingot of the alloy to a series of hot and cold rollingtreatments followed by annealing, as described hereinbefore, until thethickness is about three and one-third times that desired in theconnector. The annealed sheet is then cold worked to iinal thickness,for instance about 0.015", and blanks of the desired shape stampedtherefrom. The blanks are then perforated at 5, indented at 6, and bentto form the sleeve portion 7 of the electrical connector 1.

it is to be understood that small amounts of impurities may be permittedin the copper-manganese-iron-phosphorus alloy of this invention,provided such impurities are not present in suiiicient amount todeleteriously alter the conductivity, strength and other desirableproperties of the alloy. it is also to be understood that although theinvention is described with particular reference to electricalconnectors for electronic tubes, it may have other uses as connectors inswitches and the like, all of which are contemplated to fall within thescope of the invention. Although many specific compositions and detailsare set forth in the foregoing, it will be understood that variouschanges may be made without departing from the spirit and scope of thisinvention and that this invention is therefore not to be limited to suchcornt positions and details except as set orth in the appended claims.

This application is a continuation-in-part of our copending applicationSerial No. 112,223, led August 25, i949, now abandoned.

Having thus described the invention, what is claimed and desired tosecure by Letters Patent is:

l. A cold-worked alloy characterized by having a phosphorus content offrom about 0.16% to 0.58%, an iron content of from about 0.02% to 0.89%,and a manganese content of from about 0.27% to 1.12%, with the balancesubstantially copper.

2. A cold-worked alloy characterized by having a phosphorus content offrom about 0.19% to 0.51%, an iron content of from about 0.15% to 0.76%,and a manganese content of from about 0.47% to 0.94%, with the balancesubstantially copper.

3. A cold-worked alloy characterized by having a phosphorus content offrom about 0.33% to 0.36%, an iron content of from about 0.42% to 0.49%,and a manganese content of from about 0.67% to 0.72%, with the balancesubstantially copper.

4. An electrical conductor characterized by an electrical conductivityof at least 50% i. A. C. S., a tensile strength of at least 75,000pounds per square inch, and formed of a cold-worked copper-base alloycomposed of from about 0.16% to 0.58% phosphorus, from about 0.02% to0.89% iron, and from about 0.27% to 1.12% manganese, with the balancesubstantially copper.

5. An electrical conductor characterized by an electri- 5 calconductivity of at least 60% I. A. C. S., a tensile strength of at least80,000 pounds per square inch, and formed of a cold-worked copper-basealloy composed of from about 0.19% to 0.51% phosphorus, from about 0.15%to 0.76% iron, and from about 0.47% to 0.94% manganese, with the balancesubstantially copper.

6. An electrical conductor characterized by an electrical conductivityof at least 60% I. A. C. S., a tensile strength of at least 80,000pounds per square inch, and formed of a cold-worked copper-base alloycomposed of from about 0.33% to 0.36% phosphorus, from about 0.42% to0.49% iron, and from about 0.67% to 0.72% manganese, with the balancesubstantially copper.

7. An electrical conductor characterized by an electrical conductivityof at least I. A. C. S., a tensile strength of at least 75,000 poundsper square inch, and formed of a cold-worked copper-base alloy composedof from about 0.16% to 0.58% phosphorus, from about 0.02% to 0.89% iron,and from about 0.27% to 1.12% manganese, with the balance substantiallycopper, the percentages of phosphorus, iron and manganese correspondingto a point within the volume E of the three-dimensional diagram ofFigure 8 of the drawings.

8. An electrical conductor characterized by an electrical conductivityof at least I. A. C. S., a tensile strength of at least 80,000 poundsper square inch, and formed of a cold-worked copper-base alloy composedof from about 0.19% to 0.51% phosphorus, from about 0.15% to 0.76% iron,and from about 0.47% to 0.94% manganese, with the balance substantiallycopper, the percentages of phosphorus, iron and manganese correspondingto a point within the volume F of the threedimensional diagram of Figure8 of the drawings.

9. An electrical conductor characterized by an electrical conductivityof at least 60% l. A. C. S., a tensile strength of at least 80,000pounds per square inch, and formed of a cold-worked copper-base alloycomposed of from about 0.33% to 0.36% phosphorus, from about 0.42% to0.49% iron, and from about 0.67% to 0.72% manganese, with the balancesubstantially copper, the percentages of phosphorus, iron and manganesecorresponding to a point within the volume F of the three-dimensionaldiagram of Figure 8 of the drawings.

10. An electrical conductor characterized by having a phosphorus contentin the range of 0.13% to 0.58%, an iron content of from 0.15% to 0.76%,and a manganese content of from 0.47% to 0.94%, with the balancesubstantiallyI copper, the percentages of phosphorus, iron and manganesecorresponding to a point within the volume E of the three-dimensionaldiagram of Figure 8 of the drawings, said conductor having an electricalconductivity of at least 50% I. A. C. S., and a tensile strength of atleast 75,000 pounds per square inch.

11. An electrical conductor characterized by having a phosphorus contentin the range of from about 0.16% to 0.58%, an iron content of from 0.42%to 0.49%, and a manganese content of from 0.67% to 0.72%, with thebalance substantially copper, the percentages of phosphorus, iron andmanganese corresponding to a point within the volume F of thethree-dimensional diagram of Figure 8 of the drawings, said conductorhaving an electrical conductivity of at least 60% I. A. C. S., and atensile strength of at least 80,000 pounds per square inch.

l2. The method of making an electrical conductor hav- J ing anelectrical conductivity of at least 50% I. A. C. S.,

and a tensile strength of at least 75,000 pounds per square inch, whichcomprises providing an alloy having a phosphorus content of from about0.16% to 0.58%, an iron content of from about 0.02% to 0.89%, and amanganese content of from about 0.27% to 1.12%, with the balancesubstantially copper, and with the percentages of phosphorus, iron andmanganese corresponding to a point within the volume E or thethree-dimensional diagram of ligure 8 of the drawings, with an annealedstructure and a dimension about three and one-third times that desiredfor the conductor, and cold-working the alloy to a reduction in saiddirection of about 70%. K

13. The method of making an electrical conductor having an electricalVconductivity of at least 60% I. A. C. S., and a tensile strength of atleast 80,000 pounds per square inch, which comprises providing an alloyhaving a phosphorus content of from about 0.33% to 0.36%, an ironcontent of from about 0.42% to 0.49%, `and a manganese content of fromabout 0.67% to 0.72%, with the` balance substantially copper, and Withthe percentages of phosphorus, iron and manganese correspond- 8 ing to apoint within the volume F of the three-dimensional diagram of Figure 8of the drawings, with an annealed structure and a dimension about threeand onethird times that desired for the conductor, and cold-V Workingthe alloy toa reduction in said direction of about 70% n ReferencesCited in the file of this patent UNITED STATES PATENTS Hensel et al.July 12, 1938 Crampton Apr. 25, 1939

7. AN ELECTRICAL CONDUCTOR CHARACTERIZED BY AN ELECTICAL CONDUCTIVITY OFAT LEAST 50% I. A. C. S., A TENSILE STRENGTH OF AT LEAST 75,000 POUNDSPER SQUARE INCH, AND FORMED OF A COLD-WORKED COPPER-BASE ALLOY COMPOSEDOF FROM ABOUT 0.16% TO 0.58% PHOSPHORUS FROM ABOUT O.02% TO 0.89% IRON,AND FROM ABOUT 0.27% TO 1.12% MANGANESE, WITH THE BALANCE SUBSTANTIALLYCOPPER, THE PERCENTAGES OF PHOSPHORUS, IRON AND MANGANESE CORRESPONDINGTO A POINT WITHIN THE VOLUME E OF THE THREE-DIMENSIONAL DIAGRAM OFFIGURE 8 OF THE DRAWINGS.